bq24901

(1) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

The bq24901 Li-Ion charge management devices are designed specifically for off-line charger applications.

The bq24901 resides on the secondary-side of the transformer and provides the control feedback to a variety of primary side controllers. The bq24901 offers current or voltage regulation feedback, temperature monitoring, charge status, and adjustable charge termination, in a single monolithic device. During battery-absent or charge-complete conditions, the bq24901 continuously regulates the secondary-side voltage, used as VCC supply to the device.

The bq24901 features a time-limited precon ditioning phase to condition deeply discharged cells. The pre-conditioning phase is achieved by linear regulation in the secondary side. Following preconditioning, the bq24901 regulates the charge current to the value set by the external current sense resistor. Once the battery reaches the charge voltage, the voltage regulation loop takes over and completes the charge cycle. The accuracy of the voltage regulation is better than ±30mV. Charge is terminated based on minimum current. The minimum current level is set through TADJ pin. An internal five-hour charge timer provides a backup for charge termination.

The bq24901 is designed to reliably detect battery insertion and removal conditions, including packs with open protectors. Other standard features include a recharge feature activated when the battery voltage falls below the VRCH threshold.